Venom is key to Komodo dragon's killing power

Far from harbouring toxic bacteria in their mouths as long believed, Komodo dragons produce venom from complex glands in their lower jaws, according to a team led by Bryan Fry of the University of Melbourne, Australia.

However, magnetic resonance imaging of a preserved Komodo head by the Fry team from the Museum of Natural History at Humboldt University in Berlin revealed an alternative explanation: huge venom glands opening to ducts at the front of the jaw.

Shocking bite

The finding was confirmed when the team surgically removed the glands from a terminally ill Komodo at Singapore Zoo. Genetic and chemical analysis revealed a large array of venomous substances – including those that prevent blood clotting and widen blood vessels. These would cause blood pressure to plummet, potentially inducing shock, if injected into a mammal.

The team's computer modelling of the Komodo bite suggests a relatively weak bite – a maximum bite force of 39 newtons, compared to 252 N for an Australian saltwater crocodile of the same size – but the powerful neck and razor-sharp teeth are ideal for a slashing attack.

"They slash and pull back, but it's the venom that nails it. It lowers blood pressure, and stops blood clotting. Prey goes into shock and can't even struggle," says Fry. The venom could lead to the development of novel pharmaceuticals, he adds.

Missing the obvious

The existence of venom also fits with Fry's own experiences observing a keeper at the Singapore Zoo who was bitten by a Komodo. "He was very frightened. He bled for three or four hours. That doesn't happen with a bacterial infection; a normal wound would have close by then," says Fry.

By comparing the ecology and skeletal structure of the Komodo, Megalania and the Lace monitor – a reptile closely related to both – the Fry team concluded that Megalania is the largest ever venomous creature.

The venom gland "is not a trivial structure, [but] a big bulge" on the lower jaw, says Fry, who compares previous ignorance of the Komodo dragon's venomous capabilities as akin to "missing the teeth on great white sharks and saying they are plankton eaters".

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